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Introduction

This page explains how to get the config files for using the T2 audio device, which allows use of the 3.5mm headphone port, the built in speakers, the built in mic and the headphones' mic.

Before you proceed, make sure you already have apple_bce loaded by running lsmod | grep apple_bce. If not, follow the instructions on how to setup the BCE module.

Enable Pass-Through Kernel Parameters

Cat cat /proc/cmdline and ensure that your kernel parameters contain intel_iommu=on iommu=pt pcie_ports=compat.

If not present, you'll have to update your bootup kernel params:

  • edit /etc/default/grub and update GRUB_CMDLINE_LINUX to include intel_iommu=on iommu=pt pcie_ports=compat
  • Apply your edits by running sudo update-grub on ubuntu or sudo grub-mkconfig -o /boot/grub/grub.cfg for other distros
  • Reboot and ensure cat /proc/cmdline contains those params

systemd-boot

If you use systemd-boot you'll instead edit your boot conf files to add intel_iommu=on iommu=pt pcie_ports=compat to the options line. The files to edit will have the .conf extension and be in the loader/entries/ folder on your EFI partition. This will most likely be /boot/efi/loader/entries

Audio Configuration Files

In most scenarios, you should use these files, following the instructions in that gist's README.md.

Special scenarios are:

Using Pipewire instead of Pulseaudio

You'll need to modify the /lib/udev/rules.d/91-pulseaudio-custom.rules file from the links above.

SUBSYSTEM!="sound", GOTO="pulseaudio_end"
ACTION!="change", GOTO="pulseaudio_end"
KERNEL!="card*", GOTO="pulseaudio_end"

-SUBSYSTEMS=="pci", ATTRS{vendor}=="0x106b", ATTRS{device}=="0x1803", ENV{PULSE_PROFILE_SET}="apple-t2.conf"
+SUBSYSTEMS=="pci", ATTRS{vendor}=="0x106b", ATTRS{device}=="0x1803", ENV{PULSE_PROFILE_SET}="apple-t2.conf", ENV{ACP_PROFILE_SET}="apple-t2.conf"

LABEL="pulseaudio_end"

Note: The updated locations for the files in the links above for Pipewire distributions will be:

  • /usr/share/alsa/cards/AppleT2.conf
  • /usr/share/alsa-card-profile/mixer/profile-sets/apple-t2.conf
  • /usr/lib/udev/rules.d/91-pulseaudio-custom.rules

Issues

  • Some people are unable to get audio input to work. You may have to use a separate microphone.
  • All of apple's fancy tuning of the speakers is done in macOS, we don't have anything like that at the moment.

Approaches to fixing low microphone volume

Pulseaudio (2019 16" MacBook Pro)

Monitor the volume of the microphone and set it back to 400% when a sudden drop in the volume of the microphone occurs (something sets in to 100%. This will help to have consistent microphone volume during video/audio calls.

KDE

The "Audio Volume" dialog / Audio in System Settings allow users to "Raise maximum volume", allowing to go past 100%. This does not offer a great deal of flexibility, it might work for getting acceptable recordings however.

EasyEffects with Pipewire

EasyEffects is a tool to control and modify audio streams when using pipewire. Compared to the KDE approach mentioned above using input plugins like "Autogain" offers a lot more fine grain control and higher volume boosts.